Castiel was seen charging at Lucifer in the alternate reality in a bid to keep him contained while the rift sealed. But upon returning to the original reality, he was unceremoniously stabbed through the back by Lucifer with an angel blade – right in front of a horrified Dean and Sam.

One theory going around is that Jack (aka the son of Lucifer and Kelly Kline) could resurrect Castiel (and maybe even Crowley)... or perhaps there's an alternate reality version of Castiel – just like viewers saw Alternate Bobby Singer.

We'll find out what happens when season 13 begins later this year.

Supernatural returns to The CW this autumn, and fans in the UK can watch the show on E4.